Maybe if they captured and operated European ships with a lot more firepower it might impress the Qing. Especially if they start raiding beyond Canton. As formidable as the pirates were, they were still using local technology, small vessels with small cannons and spearmen.
True, although they had 70,000 men, and with their success, and wealth, could get their numbers up to 100,000 in a year. Their numbers, troops, AND power is soo great, the Qing could probably see it as a threat to their entire dynasty. Also, it's probably likely they'll get modern weapons. Maybe if western powers are willing to trade with the pirates for modern European technology for cheap deals. From all the raiding they've done, and could do, they can get modern technology. If the pirates get modern technology, The Qing might be on verge of collapse. THEN the Qing will be forced too modernize their navy, get rid of corruption, and a lot of their problems.